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Turtle Tracks - History and Conservation

San Diego Bay’s green sea turtles were first studied by Margie Stinson, who was completing her graduate studies at San Diego State University. Stinson is currently a Biology professor at Southwestern College in Chula Vista and continues to visit her old study site with her students. Her 1984 Master’s Thesis1 includes an exhaustive review of this species’ presence in San Diego Bay throughout the past two centuries, and is summarized below.

San Diego Bay is the only place along the west coast of the United States where sea turtles are currently known to aggregate. The first mention of sea turtles in San Diego newspapers occurred in 1857, when the whaling Captain Bogart arrived in San Diego with sea turtles that he had captured in Mexico. He set up turtle pens on the shores of Point Loma with the intent of starting up a turtle meat business. During a series of storms that year, approximately 100 turtles broke away and escaped into the bay. Whether these were the first turtles introduced to San Diego or sea turtles already existed here is unknown, but many researchers believe that the turtles have been migrating to San Diego Bay from Mexico for hundreds of years.

Numerous newspaper accounts spanning the years 1872 through 1903 document the capture of sea turtles in both San Diego Bay and Mission Bay. Sea turtles were commonly taken from San Diego Bay and sold to local restaurants for 4 cents a pound. Two local men interviewed by Stinson for her thesis reported that it was quite common to see sea turtles in San Diego Bay up until World War I, after which there is no solid evidence of San Diego Bay turtle sightings until the mid-1960s. Whether the absence of turtle sightings in newspapers during this time period reflects an actual local disappearance of this species or is a reflection of the media’s attention on world events is unknown; however the market for sea turtle meat in San Diego began to deteriorate by 1921.

In 1976, Captain Eddie McEwen, one of the most famous fishing captains of the eastern Pacific, convinced Stinson of the existence of sea turtles in south San Diego Bay. After seeing them for herself, she decided to devote her graduate research to their natural history and biology. Eventually she completed two volumes of research (nearly 600 pages) that focused on two aspects of sea turtle biology: (1) the biology of San Diego’s population of green sea turtles, and (2) the migration and seasonal biology of all species of sea turtles in the eastern Pacific. Stinson was the first scientist to study the same individual wild sea turtles for a period of years, and her research inspired many other biologists to follow in her footsteps.

The Eastern Pacific Green Sea Turtle was listed as an endangered species in 1978, promoting a growing awareness of the importance of sea turtle protection and research. In the 1980s, marine biologists Dr. Peter Dutton and Donna McDonald expanded on Stinson’s research and formed the San Diego Sea Turtle Team, a group of citizens who monitored the turtles. Currently, San Diego Bay serves as a research site for the Marine Turtle Research Program, part of the Southwest Fisheries Science Center’s Protected Resources Division of the National Oceanic and Atmospheric Administration (NOAA-Fisheries), and led by Dr. Peter Dutton since 1995. Stinson’s pioneering successes, challenges, and failures became the foundation for their research in San Diego Bay, which consists of biological sampling of skin and blood, sonic tracking, and satellite telemetry.

Sea Turtle Conservation

Throughout history, the greatest cause of declining sea turtle populations is the commercial harvest of eggs and meat, followed by the use of their skin and shells for leather and jewelry. Incidental bycatch of sea turtles through commercial shrimp trawling and long line fisheries and destruction or alteration of nesting and foraging areas are also current sources of mortality. Conservationists are working with the fisheries fishing fleets to adapt their gear and fishing strategies in an effort to decrease the occurrence of accidental deaths.

Although turtles in San Diego Bay are protected by the South San Diego Bay National Wildlife Refuge and fishing or capturing turtles is illegal in the U.S. and in Mexico, a thriving black market for sea turtle meat exists within mere miles of the Refuge across the Mexican border and throughout Mexico. Although sea turtles have been protected in Mexico since 1990, sea turtle meat, or caguama, is often consumed as a traditional dish during religious feasts and other celebrations and festivals. The Grupo Tortuguero researchers estimate that approximately 35,000 sea turtles are captured each year in the waters of Baja California and the Sea of Cortez to be sold on the black market in Mexico, Arizona and California. Officials, biologists and citizens from both sides of the border are working together to eliminate these illegal threats.

1Stinson, Margie L. (1984). Biology of sea turtles in San Diego Bay, California, and in the northeastern Pacific Ocean. Volume 1. Master’s Thesis, San Diego State University, San Diego, California.